1. Field of the Invention
The present invention relates to a multilayer ceramic substrate, a method for manufacturing the same, and a piezoelectric resonator component including the multilayer ceramic substrate, and more particularly, to an improvement of the material composition of the internal electrode included in the multilayer ceramic substrate.
2. Description of the Related Art
A multilayer ceramic substrate of interest to the invention has been disclosed in Japanese Unexamined Patent Application Publication 2001-30419 (Patent Document 1).
The multilayer ceramic substrate disclosed in Patent Document 1 is manufactured by a method including the steps of preparing a green composite including a base layer including, for example, a glass powder and a ceramic powder, a first functional material layer including a dielectric ceramic powder, and a second functional material layer including a magnetic ceramic powder, firing the green composite at a predetermined temperature to sinter at least a portion of the glass powder, and to allow a portion of the glass included in the base layer to diffuse or flow into the first and the second functional material layer, thereby fixing to each other the dielectric ceramic powder and the magnetic ceramic powder contained in the first and second functional material layers to each other without sintering.
This method enables firing at a relatively low temperature, and thus, achieves a multilayer ceramic substrate having superior specific electrical characteristics, such as a dielectric property, magnetism, resistance, and/or an insulating property.
The method of Patent Document 1 reduces the shrinkage of the base layer and the first and second functional material layers during firing.
The multilayer ceramic substrate includes internal electrodes disposed along the base layer and/or the functional material layers. If the internal electrodes are made of an electroconductive paste, they are sintered to shrink by firing. Consequently, a relatively high stress exists at the interface between the internal electrode and the base layer and/or the interface between the internal electrode and the functional material layer after the sintering.
In the manufacture of the multilayer ceramic substrate, in general, a mother composite is prepared through a firing step, and cut into a plurality of multilayer ceramic substrates with, for example, a dicer. By this cutting, ends of specific internal electrodes may be exposed at the cut surfaces.
However, the residual stress may cause the interface between the internal electrode and the base layer and/or the interface between the internal electrode and the functional material layer to crack when the mother composite is cut into multilayer ceramic substrates.